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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alex Deucher <alexander.deucher@amd.com>,
        Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>,
        Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 4.19 167/191] drm/amd/display: Dont invoke kgdb_breakpoint() unconditionally
Date:   Tue,  3 Nov 2020 21:37:39 +0100
Message-Id: <20201103203248.105268892@linuxfoundation.org>
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From: Takashi Iwai <tiwai@suse.de>

commit 8b7dc1fe1a5c1093551f6cd7dfbb941bd9081c2e upstream.

ASSERT_CRITICAL() invokes kgdb_breakpoint() whenever either
CONFIG_KGDB or CONFIG_HAVE_KGDB is set.  This, however, may lead to a
kernel panic when no kdb stuff is attached, since the
kgdb_breakpoint() call issues INT3.  It's nothing but a surprise for
normal end-users.

For avoiding the pitfall, make the kgdb_breakpoint() call only when
CONFIG_DEBUG_KERNEL_DC is set.

https://bugzilla.opensuse.org/show_bug.cgi?id=1177973
Cc: <stable@vger.kernel.org>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/amd/display/dc/os_types.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/amd/display/dc/os_types.h
+++ b/drivers/gpu/drm/amd/display/dc/os_types.h
@@ -57,7 +57,7 @@
  * general debug capabilities
  *
  */
-#if defined(CONFIG_HAVE_KGDB) || defined(CONFIG_KGDB)
+#if defined(CONFIG_DEBUG_KERNEL_DC) && (defined(CONFIG_HAVE_KGDB) || defined(CONFIG_KGDB))
 #define ASSERT_CRITICAL(expr) do {	\
 	if (WARN_ON(!(expr))) { \
 		kgdb_breakpoint(); \